Power Transistor BD681 NPN Darlington, TO-126

Power Transistor BD681 NPN Darlington, TO-126

Transistors

Reference: TRBD681

Part.No: BD681

€1.20

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The BD681 is a high-voltage NPN Darlington Transistor in a TO-126 package. Designed for driving medium-power loads such as relays, solenoids and motor control circuits directly from logic-level signals.

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Description
Product Details

BD681 Darlington Power Transistor – Medium-Load Switching & Relay Driver

The BD681 is a robust NPN Darlington transistor optimized for medium-power switching and amplification. Its high current gain (hFE) and TO-126 package make it ideal for automation boards, relay drivers and solenoid control, delivering reliable performance where moderate current and voltage handling is required.

Functions & Applications

High DC Gain (hFE): Darlington configuration enables direct logic-level driving of relays and solenoids.
Integrated Base-Emitter Diode: Built-in protection reduces external component count in typical relay circuits.
TO-126 Package: Moderate mounting area with good thermal contact, suitable for breadboard and PCB assembly.
Reliable Switching: Proven performance in automation, motor control and industrial switching applications.

Technical Specifications

Parameter	Value / Specification
Transistor Type	Darlington
Polarity / Channel	NPN
Package / Case	TO-126
Collector-Emitter Voltage (Vceo)	80V
Max Collector Current (Ic)	4A
Power Dissipation (Pd)	12.5W
Mounting Type	Through-Hole (THT)

Frequently Asked Questions

Q: Can the BD681 drive a 12V relay with a coil current of 200mA?
A: Yes. The BD681 supports up to 4A collector current, so 200mA is well within its limits. Always connect a flyback diode (e.g., 1N4007) across the relay coil to protect the transistor from inductive spikes.

Q: What is the complementary PNP Darlington part for BD681?
A: The complementary PNP Darlington transistor is the BD682, offering similar voltage and current ratings in the opposite polarity.

Note: Price refers to one (1) piece. The component is shipped in bulk without individual packaging.

Transistor Type: Darlington
Transistor Polarity / Channel: NPN
Transistor Case Style: TO-126

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